Pro Ball from Socom Tactical are good. Gunfire Rockets and BB King are also a couple I've tried and had no issues. Just avoid Nuprol.
As for weight, that's a personal decision really. The lighter the BB the faster it gets to your target but the quicker it'll shed its energy and the less inertia it can hold from the hop - so basically heavier weights go further but get there slower. I'd say start at above .30g (maybe with .36g for instance) then work your way up as high as above .40g if you're not getting the distance you need.
Most heavy weight BBs are now hydrophilic and will adsorb water over time, so keep that in mind. Once you open the bag you're advised to use them within 3 months and keep the bag (and its silica gel packet) sealed up whenever possible. ASG have
also released their own heavy weight BBs that don't appear to be hydrophilic so I may pick some up. Not sure if anyone on here has had a chance to test them yet, but other ASG BBs are quite good.